IC-NRLF 


SB    27fi    072 


GIFT   OF 

PROF.  w.B. 


AN  OUTLINE 


OF 


QUALITATIVE    ANALYSIS, 


FOR    BEGINNERS, 


BY 


JOHN  T.  STODDARD,  PH.  D., 

PROFESSOR    OF   CHEMISTRY   IN   SMITH   COLLEGE. 


(|team  ^te^  o^  ^a^et-tc  H^int 

1883. 


Copyright  by 

JOHN  T.    STODDARD. 


PREFACE, 


The  desire  to  place  in  the  hands  of  my  students  who  are 
beginning  the  study  of  Qualitative  Analysis  a  clear,  concise, 
and  simple  Outline  of  the  subject,  has  led  me  to  the  prepara- 
tion of  this  little  work. 

Much  that  is  found  even  in  elementary  books  is  purposely 
omitted  in  this.  Manipulation  can  only  be  satisfactorily 
learned  from  practical  demonstration.  Writing  of  equations 
and  drawing  up  of  analytical  tables  are  valuable  exercises  for 
the  student.  Hence  the  little  book  presents  only  an  OUTLINE, 
which  is  to  be  filled  in  by  the  student  with  the  teacher's  assis- 
tance. 

The  method  which  its  arrangement  suggests  has  been  chosen 
as  the  one  best  calculated  to  give  the  student  an  intelligent 
grasp  of  the  subject,  and  help  him  to  become  more  than  a  mere 
analytical  machine. 

The  student  is  expected  to  make  all  the  reactions  and  ex- 
press them  in  written  equations.  When  this  has  been  done 
for  the  members  of  a  group  of  metals,  a  few  solutions,  each 
containing  one  or  more  members  of  the  group,  are  given  and 
analyzed  according  to  the  directions.  The  exercises  on  the 
group  are|]then  to  be  worked  out.  When  each  of  the  groups 

237339 


IV  PREFACE. 

has  thus  been  thoroughly  studied,  a  number  of  solids  and  so- 
lutions are  given  for  systematic  examination  for  all  the  groups. 
These  are  at  first  of  the  simplest  composition,  and  increase 
gradually  in  complexity  and  analytical  difficulty. 

The  detection  of  acids  is  now  taken  up  in  the  same  way, 
except  that  an  examination  for  metals,  of  course,  always  pre- 
ceeds  that  for  the  acids. 

Finally,  a  large  variety  of  substances  is  given  for  complete 

analysis. 

J.  T.  s. 

Smith  College  Laboratory. 
Dec.  25,.  1882. 


UN  iv  o 


I. 


DETECT IOJST  OF  THE  METALS. 


SECTION  I. 

GROUPING   OF   THE   METALS. 


Group  I.  Metals  which  are  precipitated  as  chlo- 
rides by  HC1  :  Silver  and  Mercury  (ous)  completely,. 
Lead  incompletely, 

Group  II.  Metals  not  falling  under  Group  I, 
which  are  precipitated  as  sulphides  from  acid  (HC1) 
solution  by  H2S  : — 

Sub-group  A:  Sulphides  insoluble  in  (NH4)2S  : 
Mercury  (ic),  Lead,  Bismuth,  Copper,  Cadmium. 

Sub-group  B  :  Sulphides  soluble  in  (NH4)2S  :  Tin, 
Antimony,  Arsenic,  Gold,  Platinum. 

Group  III.  Metals  not  falling  under  Groups  I 
and  II,  which  are  precipitated  as  hydroxides  bv 
NH4OH  in  the  presence  of  NHAC1  :  Iron,  Chro- 
mium, Aluminium. 


'.ANALYSIS. 

Group  IT.  Metals  not  falling  under  Groups 
I-III,  which  are  precipitated  as  Sulphides  by 
(NH4)2S  :  Nickel,  Cobalt,  Manganese,  Zinc. 

Group  Y.  Metals  not  falling  under  Groups  I-IV, 
which  are  precipitated  as  Carbonates  by  (NH4)2C03  : 
Barium,  Strontium,  Calcium. 

Group  VI.  Metals  not  falling  under  Groups  I-V 
and  having  no  common  precipitant :  Magnesium, 
Potassium,  Sodium,  Ammonium. 


SECTION  II. 

REACTIONS    OF    METALS    AND     ANALYSIS    OF    GROUPS. 


Group  I. 

REACTIONS. 

Silver.     Ag1.    Solution  for  reactions,  AgN03. 
HC1  precipitates  white   curdy  AgCl;  soluble  in 
and  in   KON  ;   reprecipitated   by  HN03  ; 
darkens  on  exposure  to  light. 

2.  H2S  or  (NH^jjS  precipitates  black  AgaS  ;  solu- 
ble in  boiling  HN03. 

3.  NH4OH    precipitates  —  from     neutral    solution 
only  —  brown   Ag30  ;    readily    soluble   in    excess   of 


4.  NaOH  precipitates  brown  Ag20. 

5.  K2Cr04  precipitates  dark  red  Ag2Cr04  ;  soluble 
in  HN03  or  in  NH4OH. 

6.  KI  precipitates  yellowish  Agl. 

7.  Na2HP04  precipitates  yellow  Ag3P04. 

8.  Cu   and   some  other  metals  precipitate  metal- 
lic Ag. 

9.  (a)   Heated  with  Na2C03  on  charcoal  before  the, 
blowpipe,    solid    compounds  of    silver  yield  bright, 
malleable   globules  of   Ag,    (b)  which  are  soluble  in 
HN03. 

Characteristic  Reaction,  L 


QUALITATIVE    ANALYSIS. 

Lead.     Pb".     Solution  for  reactions,  Pb2N03. 

10.  HC1  precipitates  (incompletely)  white  PbCl2 ; 
soluble  in  boiling  H20,  and  crystallizes  from  this  so- 
lution on  cooling ;  converted  by  NH4OH  into  white 
Pb.CtiEfoCl,  which  is  insoluble  in  H20. 

11.  H2S  or  (NH4)2S  precipitates  black  PbS  ;  solu- 
ble in  hot  HN03. 

12.  NH4OH  precipitates  a  white  basic  salt. 

13.  NaOH  precipitates  white  Pb(OH)2 ;  soluble  in 
excess. 

n.4j)K2Cr04  precipitates  "chrome-yellow"  PbCr04; 
soluble  in  NaOIi  ;  soluble  with  difficulty  in  UNO,. 

(L5J  KI  precipitates  bright  yellow  PbI2  ;  soluble  in 
boiling  H20,  and  crystallizes  from  this  solution,  on 
cooling,  in  golden  scales. 

J     (16)  H2S04   precipitates   white  PbS04  ;    soluble  jn 
ammonium  tartrate  or  NaOLL 

17.  Zn  precipitates  metallic  Pb  in  crystalline  form. 

18.  Compounds  of   Pb,  heated   with    Na2C03   on 
charcoal,   yield   soft,   malleable,    and   easily   fusible 
globules   of  Pb,   and  a  yellow  incrustation  of  PbO 
on  the  charcoal.     The  globules  are  soluble  in  IIN03. 

Characteristic  Reactions,  14,  15,  16. 

Mercury.  Hg".  Mercurou*  flalfa.  Solution  for 
reactions,  Hg22N03. 

1Q.  HC1  precipitates  white  HgaCl8  (calomel)  ;  con- 
verted by  NH4OH  into  black  NH2LIg2Cl. 

20.   H2S  or  (N1I4)2S  precipitates  black   fIg2S  ;    in- 
soluble in  hot  HNO8. 
•   ^1.   NH4OH   precipitates  black  NII2Ug2N03. 


GROUP    I  ;     ANALYSIS.  5 

22.  NaOH  precipitates  black  Hg20  ;    decomposes 
readily  into  HgO  and  Hg. 

23.  K2Cr04  precipitates  dark  red  basic  chromate  ; 
soluble  with  difficulty  in  HN03. 

24.  KI  precipitates  yellowish-green  Hg3I2. 

25.  SnCl2  precipitates  grey  Hg. 

26.  Cu  and  some  other  metals  precipitate  metal- 
lic Hg. 

27.  Compounds   of    Hg   yield   the   metal   readily 
when  heated  with  Na2C03  in  a  small  tube.     Hg  is 
volatile   and   condenses   on  the  cooler  parts  of  the 
tube  ;  soluble  in  HN03. 

Characteristic  Reactions,  19,  27. 


ANALYSIS. 

(a)  Add  HC1  until  no  further  precipitation  occurs; 
filter  and  wash  with  cold  water.     The  filtrate  may 
contain  Groups  II-VI.     The  white  precipitate  con- 
.sists  of  one  or  more  of  the  chlorides  of  Group  I  : 
AgCl,  PbCli,  Hg2Cl2. 

(b)  Add  boiling  H20  to  the  precipitate  on  the  fil- 
ter (cf.10).     Test  the  filtrate  for  Pb  by  10  and  14. 

If  Pb  is  found,  the  precipitate  is  washed  repeatedly 
with  hot  water  until  free  from  it. 

A  residue  insoluble  in  hot  water  indicates  AgCl, 
Hg2Cl2,  or  both. 

(c)  Add  NII.OH  ;    Hg2Cl2  is  blackened    (cf.  19), 
while    AgCl  is   dissolved    (cf.   1),    and   its   presence 
proved  by  adding  HN03. 

The  black  residue  containing  Hg  is  tested  by  27. 


6  QUALITATIVE    AXALYSIS. 

EXERCISES. 

I.  Draw  up  a  table  for  the  analysis  of  this  group. 

II.  Devise   another   method  for  the  analysis  of  a 
solution  containing  the  members  of  this  group. 

III.  if  PbCl2  is  not  completely  removed  from  the 
precipitate  before  adding  NH4OH,  how  is  it  affected 
by  this  reagent  ? 

IV.  Give  the  important  compounds  of  the  members 
of  this  group  ?     Describe  their  appearance  and  uses. 

Grl-Ollp     IJ. 


SUB-GKOUP     A. 

Hg,   Pb,  Bi,  Cu  antt  Cd. 

REACTIONS. 

i 

Mercury.     Hg".     Mercuric  Salts.     Solution   for 
rejections,  HgCl2. 


H8S,  added  by  degrees,  produces,  first,  a  white 
precipitate,  which  changes  to  orange,  brownish  red, 
and  finally  to  black  HgS.  This  is  insoluble  in  hot 
HN03 ;  soluble  in  aqua  regia. 

29.  NH4OH    precipitates      "white     precipitate," 
NH2HgCl. 

30.  NaOH  precipitates  yellow  HgO. 

31.  K2CrO4  precipitates  an  orange  basic  chrumate; 
readily  soluble  in  HN03. 

32.  KI  precipitates  yellow  HgI2,  which  rapidly  be- 
comes scarlet. 

/  (§3)  SnCl2  precipitates  white  Hg2Cl2  ;    if  added  in 
excess,  grey  metallic  Hg. 


GROUP    II.    A   ;     REACTIONS.  7 

34.  Reactions  26  and  27  for  raercurons  salts. 
Characteristic  Reactions,  28  and  33. 

Lead.  Pb".  PbS  is  precipitated  by  H2S  even 
from  solutions  of  PbCl2 ;  so  that  lead  belongs  to  both 
the  first  and  second  groups.  Of.  reactions,  10-18. 

Bismuth.     Bim.     Solution  for  reactions,  BiCl3. 

35.  H2S  precipitates  black  Bi2S3;  soluble  in  HN03. 

36.  NH4OH  precipitates  white  BiO.Oli  ;    becomes 
yellow  Bi203  on  boiling. 

37.  NaOH  precipitates  same. 

38.  K2Cr04  precipitates   yellow  Bi23Cr04 ;    soluble 
in  HN03 ;  insoluble  in  NaOH. 

39.  Zn  or  Fe  precipitates  spongy  Bi. 

<f0.  H20  precipitates  BiOCl  ;  insoluble  in  tartaric 
acid. 

^y  Heated  on  charcoal  with  N"a2C03,  compounds 
of  Bi  yield  hard,  brittle  globules,  and  a  yellow  vola- 
tile incrustation  of  Bi203.  Bi  is  soluble  in  HN03  or 
aqua  regia. 

Characteristic  Reactions,  40,  41. 

Copper.     Cu".     Solution  for  reactions,  CuS04. 

42.  H2S  precipitates  black  CuS  ;  soluble  in  UNO, 
and  in  KCN. 

^3^  NH4OH  precipitates  a  greenish-blue  basic  salt, 
which  dissolves  in  excess  of  NH^OH,  forming  a  dark 
blue  solution. 

44.  NaOH  precipitates  pale  blue  Cu(OH)2  ;    con- 
verted by  boiling  into  black  OftO. 

45.  K2Cr04  precipitates  a  brownish-red  basic  chro- 
mate  ;  soluble  in  HN03  and  in  NH4OH. 


QUALITATIVE    ANALYSIS. 

46.  KCN"  precipitates  greenish -yellow  Cu(CN)2  ; 
soluble  in  excess  of  KCN.  H2S  produces  no  precipi- 
tate in  this  solution. 

**rs 

Q}i  Fe  or  Zn  precipitates  metallic  Cu.  HC1  aids 
the  reaction. 

48.  Heated  on  charcoal  with  Na2C03,  compounds 
of  Cn  yield  bright  red,  malleable  particles  without  in- 
crustation. On  dissolves  in  HN03,  and  in  cone. 
H2S04. 

Characteristic  Reactions,  43  and  47. 

Cadmium.    Cd11.    Solution  for  reactions,  Cd2N03. 
VMy  H2S  precipitates  yellow  CdS  ;  soluble  in  HN03; 
insoluble  in  KCN. 

50.  NH4OH  precipitates  white  Cd(OH)8 ;  soluble 
in  excess. 

51.  NaOH  precipitates  the  same. 

52.  K2Cr04   precipitates  a  yellow  basic  chromate  ; 
soluble  in  HN03. 

53.  KCN  precipitates  white  Cd(CN)g;  soluble  in 
excess  and  reprecipitated  as  CdS  by  H2S.     Of.  46. 

54.  Zn  precipitates  Cd  in  brilliant  scales. 

Qs)  Heated  on  charcoal  with  Na2C03,  compounds 
of  Cd  yield  no  metallic  globules,  but  a  brown  incrus- 
tation of  CdO.  Cd  dissolves  readily  in  HN03. 

Characteristic  Reactions,  49  and  55. 

PRECIPITATION  OF  GROUP  II  AND   SEPARATION  OF 

SUB-GROUPS  A  AND  B. 

(a)  Ifrthe  solution — br  filtrate  from  Group  I — con- 
tains  free  HN03,  it  must  be_evaporated  with  addition 
of  HC1  nearly  to  dryness.  (b)  Dilute  with  H80, 


GROUP   II.    A  ;     ANALYSIS.  9 


and  saturate  the  warm  solution  w^'th  H»R.     (c)  Filter 

and  wash  with  hot  H20  till  free  from  IIC1. 

The  Filtrate  may  contain  Groups  III-  VI. 

The  Precipitate  consists  of  some  one  or  more  of 
the  sulphides  of  Group  II  :  A.  HgS,  JPbS,  Bi2S3, 
CuS,  CdS  ;  B.  SnS,  SnS2,  As2S3,  Sb2S3.  " 

(d)  *  Digest   with  warm,  yellow   (NH4)2S2  for  ten 
minutes.      The  sulphides  of   Sub-group   B    dissolve 
and  are  separated  by  filtration  from  the  insoluble 
sulphides  of  Sub-group  A.     The  latter  are  washed 
with  hot  H20  till  no  longer  alkaline. 

SUB-GROUP  A.—  ANALYSIS. 

(e)  The  sulphides—  HgS,  PbS,  Bi2S3,  CuS,  CdS— 
are  boiled  with  a  small  quantity   of  strong  IIK08  ; 
the  solution  diluted  and  filtered  : 

(f)  The  residue  may  consist   of  HgS,    black  and 
heavy;  Ft>SO4,  white  aii-d  heavy  ;  Sulphur,  light  and 
floating.     Dissolve  HgS  in  aqua  regia,  expel  excess 
of  acid,  and  test  with  SnCl2  (cf.  33), 

(g)  Infiltrate  may  contain  Pb,  Bi,  Cu,  Ud.     Add 
H2S04  and  filter  if  necessary.  Al 

White  precipitate,  PbS04.     Dissolve  in 


and  test  by  14. 

(h)  The  -filtrate  may  contain  Bi,  On,  Cd.  Add 
NH4OH  and  filter  if  necessary. 

White  precipitate.  Dissolve  in  a  little  cone.  HC1  ; 
expel  excess  of  acid  and  pour  into  H20  (cf.  40). 

(i)  Filtrate  may  contain  Cu,  Cd.  If  blue,  Cu  is 
present.  Add  KCN  until  the  solution  becomes  color- 

*In  the  absence  of  Sub-group  B,  omit  this  step  and  treat  at  once  with 
HNO3  as  below  (e). 

2 


10  QUALITATIVE    ANALYSIS. 

less.  Treat  warmed  solution  with  H2S  (avoid  excess), 
yellow  precipitate  is  CdS  (cf.  53).  If  not  blue,  Cd 
alone  can  be  present.  Treat  with  H2S. 

EXERCISES. 

V.  Draw  up  a  table  for  the  analysis  of  this  group. 

VI.  Why  is  the  solution  which  is  to  be  examined 
for  Group  II  evaporated  with  HC1  before  treatment 
with  H2S  (see  a)  ? 

VII.  Why  is  it  important  to  wash  the  precipitated 
sulphides  free  from  HC1  (see  c)  ? 

VIII.  Explain  the  presence  of  S  and  that  of  PbS04 
in  the  residue  insoluble  in  HNO3  (see  f). 

IX.  If  the  nitrate  from  HgS  (see  g)  were  treated  at 
once  with  NH4OH,  what  would  the  precipitate  con- 
tain, and  how  could  it  be  examined  ? 

X.  How  may  the  color  of  the  H2S  precipitate  in- 
dicate the  presence  or  absence  of  certain  members  of 
this  group  ? 

XI.  Give  the  important  compounds  of  the  mem- 
bers of  this  group  ;  their  appearance  and  uses. 

SUB-GROUP  B  :     Sn,  Sb  and  As. 

REACTIONS. 

Tin.     a.  Sn11.     Stannous   Salts.     Solution  for  re- 
actions, SnCl2. 

56.  H2S  precipitates  dark  brown  SnS  ;    soluble  in 
yellow  (N"H4)2S2 ;    reprecipitated  as  yellow  SnS2  by 
HC1. 

57.  NII4OH  precipitates  white  Sn(OH)2. 

58.  NaOH  precipitates  same  ;  soluble  in  excess. 

59.  HgCl2  precipitates  white  Hg2Cl2  (cf.  33). 

60.  Zn  precipitates  metallic  Sn. 


GROUP   II.    B;     REACTIONS.  11 

61.  Heated  on  charcoal  with   Na2C03  and  borax, 
compounds  of  Sn    yield  white,  malleable  globules  ; 
in  the  oxidizing  flame,  slight  white  incrustation  of 
Sn02.     Sn  is  soluble  in  cone.  HC1  ;    is  converted  by 
cone.  HN03  into  insoluble  metastannic  acid. 

62.  Stannous  salts  are  converted  into  stannic  by 
oxidizing  agents  :  HN03,  01,  Fe2Cl6,  etc. 

b.   Sniv.     Stannic   Halts.     Solution  for  reactions, 
SnCl4. 

63.  H2S    precipitates    yellow    SnS2 ;     soluble    in 
(NH,)28,  in  NaOH,  and  in  hot  cone.  HC1. 

64.  NH.OH  precipitates  white  SnO(OH)2. 

65.  NaOH  precipitates  the  same;  soluble  hi  excess. 

66.  Reactions  60  and  61. 
Characteristic  Reactions  ;  a.  56,  59  ;  b.  63. 

Antimony.     Sbm.     Solution  for  reactions,  Sb013. 

67.  H2S     precipitates   orange    Sb2S3  ;    soluble    in 
(NH4)2S,   NaOH,  and  in  hot  cone.   HC1. 

68.  NH4OH  precipitates  white  Sb(OH)8. 

69.  NaOH  precipitates  same  ;  soluble  in  excess. 

70.  H20  precipitates  from  SbCl3,  white  SbO.Cl  ; 
soluble  in  tartaric  acid.    Cf.  40. 

71.  Zn  in  presence  of  of  HC1  and  Ft,  precipitates 
Sb  as  a  black  powder,  adhering  to  the  Pt.    The  black 
stain  on  the  Pt  is  not  removed  by  HC1  ;   but  warm, 
cone.  HN03  causes  the  stain  to  disappear  by  convert- 
ing Sb  into  HSb03. 

72.  Heated  on  charcoal  with  Na2C03,  compounds 
of  Sb  yield  a  white  incrustation  of  Sb203  and  hard 
brittle  globules  of  Sb,  which  are  insoluble  in   HC1  ; 
oxidized  by  HN03  ;  dissolved  by  aqua  regia. 


12  QUALITATIVE    ANALYSIS. 

Arsenic,     a.   As111.     Arsenious    Compound*.     So- 
lutions for  reactions,  Na8As08. 

73.  H2S   precipitates    yellow    As2S3  ;     soluble    in 
(NH4)2S    and    in   NaOH  ;     reprecipitated   by   HC1  ; 
nearly  insoluble  in  cone.  HC1.     Cf.  63  and  67. 

74.  NH4OH  and  NaOH  produce  no  precipitates. 

75.  AgN03  added  to  a  neutral  solution  of  an  ar- 
senite  precipitates  yellow  Ag3As03. 

76.  CuS04  added  to  a  neutral  solution  of  an  urso 
nite,  precipitates  CuHAs03,  "  Scheele's  green." 

77.  Cu  added  to  an  HC1  solution   of  arsenic  be- 
comes   coated   with   a   grey    film    of    metallic    As. 
Reinscli's  test. 

78.  Arsenious  compounds  are  converted  by  oxidiz- 
ing agents  into  arsenic   compounds.     The  simulta- 
neous reduction  of  the  oxidizing  agent  is  shown  in 
the   following   reactions  :     a.   K2Cr04   warmed  with 
arsenious   compounds  becomes  green,     c.   KMn04  is 
decolorized. 

b.   Asv.     Arsenic  Compounds.     Solution  for  reac- 
tions, NasAs04. 

79.  H2S  precipitates,  in   warm  solutions  free  from 
HN03,  AsaS3  and  S.     Cf.  73. 

80.  Cf.  74. 

81.  AgN"03,  added  to  a  neutral  solution  of  an  arse- 
nate,  precipitates  reddish  brown  Ag3As04. 

82.  MgS04  precipitates,  in  the  presence  of  NH4OH 
and  NH4C1,  white  crystalline  MgNH4As04. 

83.  Heated  on   charcoal   with    Na2C03,    all   com- 
pounds of  arsenic  are  reduced  to  As,  which  volatilizes 
with  apharacteristic  garlic  odor. 


GROUP   II.    B  ;    ANALYSIS.  13 

84.  Heated  with  charcoal  in  a  glass  tube,  a  "  mir- 
ror" of  metallic  arsenic  is  obtained. 

SUB-GROUP  B— ANALYSIS. 

(a)  The  sulphides  SnS2,  Sb2S3,  As2S3,  are  precipita- 
ted from  the  filtrate  from  Sub-group  A  by  adding 
HC1  to  acid  reaction.     Filter   and   wash   with   hot 
H20.     Boil  with  cone.  HOI  and  filter. 

(b)  The   residue,  light  yellow  As2S8,  is  converted 
into  a  soluble  arsenate  by  boiling  with  cone.  HC1  and 
a  few  crystals  of  KC103.     Test  by  82. 

(c)  The  filtrate  may  contain  Sn  and  Sb.     Add  Zn 
and  platinum  foil  to  the  acid  solution.     Both  metals, 
if  present,  are  reduced  to  the  metallic  state,  Sn  be- 
ing  deposited  on  the  Zn,   and  Sb  as  a  black  stain 
on  the  Pt.     Remove  excess  of  Zn,  wash,  add  cone. 
HC1,  warm  to  dissolve  Sn,  and  filter. 

(d)  Residue  is  black  ;  Sb  ;  remove  as  far  as  possible 
from  the  Pt ;  dissolve  in  aqua  regia  and  expel  excess 

of  acid,  dilute  and  test  with  H2S. 

(e)  Solution  may  contain  Sn  ;  expel  excess  of  acid, 
dilute  and  test  with  Hg012. 

Au  and  Pt  belong  to  this  Sub-group  and  in  the 
course  of  analysis  their  sulphides,  Au2S3  and  PtS2, 
being  insoluble  in  HC1,  remain  in  the  residue  with 
As2S3  (see  b).  By  treatment  with  HC1  and  KC103, 
they  are  dissolved  and  detected  by  the  following 
special  tests  : 

Gold.    Aum 

85.  SriCl2+SnCl4  produce  a  purplish  coloration  or 
precipitate  ;  "  Purple  of  Cassius." 


14  QUALITATIVE   ANALYSIS. 

Platinum.    PtIV 

86.   NH4C1  precipitates  yellow  crystalline  2NH4C1, 
PtCL  ;  less  soluble  in  alcohol  than  in  H20. 


EXERCISES. 

XII.  Draw  up  a  table  for  the  analysis  of  this  group. 

XIII.  Devise  another  way  for  the  detection  of  the 
members  of  this  group,  if  in  solution  by  themselves. 

XIV.  If  H2S  were  added  to  a  solution  containing  all 
the  members  of  Groups  I  and  II,  what  would  occur  ? 

XV.  What  is  the  action  of  KC103  in  b  ? 

XVI.  Give  the  important  compounds  of  the  mem- 
bers of  this  group  ;  their  appearance  and  uses. 


Group  III. 


KEACTIONS. 

Iron.     a.    Fe".     Ferrous  Salts.     Solution,  FeCl2. 

87.  (NH4)aS   precipitates  black    FeS  ;    soluble  in 
HC1. 

88.  NH4OH  or  NaOH  precipitates  white  Fe(OH)2, 
which  quickly  acquires  a  dirty  green  color,  and  ulti- 

/ately  becomes  reddish  brown  Fer(OH)  . 
89.   (NH4)2C03     or     Na2C03     precipitates     white 
FeCO^  which  rapidly  darkens  in  color. 
/    90.  K4Fe(CN)6    precipitates    white    K2Fe2(CN)6, 
which  rapidly  becomes  blue. 

91.  K3Fe(CN)6    precipitates    "  Turnbull's  blue," 
Fe3Fe2(CN)12. 


I/ 


GROUP   III  ;    REACTION'S.  15 

92.  KCNS  produces  no  coloration. 

93.  Ferrous  compounds  are  converted  into  ferric 
by  oxidizing  agents,  such  as  (a)HN03,  (b)KC103  and 
HC1,  (c)Cl. 

b.  Feiv.     Ferric  Salts.     Solution,  Fe2016. 

94.  (NH4)aS  precipitates  black  FeS  and  S. 

95.  NH4OH,  NaOH,   (NH4)2C03,  or  Na2C03  pre- 
cipitates reddish  brown  Fe2(OH)6. 

96.  K4Fe(ON)6     precipitates     "Prussian     blue," 
Fe4Fe3(CN)18. 

t/    97.   K3Fe(ON)G  produces  a  reddish  brown  color. 

98.  KCNS  produces  an  intense  blood-red  color. 

99.  Reducing    agents,    such    as   (a)H2S,    (b)S02, 
(c)Sn012,  (d)As203,  convert  ferric  into  ferrous  com- 
pounds. 

100.  Compounds  of  Fe  color  the  borax  bead  ;  yel- 
lowish red  in  the  oxidizing  flame  ;  green  in  the  re- 
ducing flame. 

101.  Heated  on  charcoal  with  Na2C03,  compounds 
of  Fe  yield  magnetic  particles,  but  no  globule. 

Characteristic  Reactions  ;  a.  91  ;  b.  96  and  98. 

Chromium.     Criv.     a.    Chromium  Salts.      Solu- 
tion, Cr23S04. 

102.  (NH4)t8  precipitates  bluish  green  Cr2  (OH)6  ; 
soluble  in  acids. 

103.  NII4OH  precipitates  Cr2(OH)6. 

104.  NaOH  precipitates  Cr2(OH)6  ;  soluble  in  ex- 
cess ;  reprecipitated  by  NH4C1  or  by  boiling. 

105.  The  oxide  and   salts   of  chromium  are   con- 
verted into  chromic  acid,  or  chromates,  by  powerful 


16  QUALITATIVE    ANALYSIS. 

oxidizing  agents ;  e.  g.  fusion  with  Na2C03  and 
KN03  on  platinum  foil  gives  yellow  K2Cr04  ;  soluble 
in  H20. 

b.    Chromic  Acid.     Solution,  K2Cr04. 

106.  Of.  5,  14,  23,  31,  38,  45,  52. 

107.  Acids     convert     yellow     K2Cr04     into     red 
K2O207  ;  alkalies  produce  the  reverse  reaction,  and 
no  precipitation. 

108.  Keducing   agents— (a)SOa,   (b)H2S,   (c)  alco- 
hol—  convert    solutions    of     chromates,     to    which 
HOI  has  been  added,  into  green  solutions  of  chrom- 
mium  salts. 

109.  All  compounds  of  chromium  color  the  borax 
bead  green. 

Characteristic  ;  color  of  solutions  and  bead,  105. 

Aluminium.     A1IV.     Solution,  A123S04. 

110.  (NH4)2S       precipitates       white      flocculent 
A12(OH)6  ;  soluble  in  acids. 

111.  NH4OH  precipitates  the  same. 

112.  NaOH  precipitates  the  same  ;    soluble  in  ex- 
cess ;  reprecipitated  by  NH4C1. 

113.  Heated  on  charcoal,  moistened  with  Co2N03 
and  heated  again,  compounds  of  Al  yield  an  infusible 
blue  mass. 

Characteristic  Reactions  ;  112,  113. 

ANALYSIS. 

(a)  If  the  solution  smells  of  H2S  (as  will  be  the 
case  if  it  is  the  nitrate  from  Group  II),  boil  until  all 
traces  of  this  gas  are  expelled.  If  a  ferrous  salt 


ANALYSIS.  17 

(test  a  few  drops  by  91)  is  present,  boil  and  add  cone. 
HN03,  a  few  drops  at  a  time,  till  it  is  completely 
converted  into  a  ferric  salt.  If  the  solution  contains 
neither  H2S  nor  ferrous  salts,  begin  at  (b). 

(b)  Add  to   the  hot  solution  NH4C1  if  the  solu- 
tion is  to  be  examined  for  the  following  groups,  and 
a  slight  excess  of  NH4OH.     Filter  and  wash  with 
hot  H20. 

The  filtrate  may  contain  Groups  IV-VI. 

The  precipitate  consists  of  one  or  more  of  the  hy- 
droxides of  Group  III:  Fe2(OH)6,  Crs(OH)6, 
A12(OII)6. 

(c)  Dissolve  the  precipitate  in  HC1,  add  excess  of 
NaOH  and  boil  a  few  minutes  ;  filter  if  necessary. 

(d)  The    precipitate    ma}r    contain    Fe    and    Or.  ^ 
Fuse  on  platinum  foil  with  Na2C03  and  KN08  ;  boil 
the  mass,  when  cool,  with  H20,  filter  if  necessary, 
boil  the  filtrate  with  acetic  acid  to  expel  C02,  and  test 
for  Or  with  PbAc2.     Of.  14. 

A  residue  insoluble  in  H20  is  dissolved  in  HC1 
and  tested  for  Fe  by  96  or  98. 

(e)  The  filtrate  may  contain  Al  ;  acidify  with  HC1 
and  add  1STH4OH.     Of.   111. 

EXERCISES. 

XVII.  Draw  up  a  table  for  the  analysis  of  this 
group. 

XVIII.  Describe  the  important  compounds  of  the 
members  of  this  group  and  their  uses. 


18  QUALITATIVE    ANALYSIS. 

Group  IV. 

REACTIONS. 

Manganese.     MnIIandIV-.     Solution,  MnS04. 

114.  (NH4)2S  precipitates  flesh-colored  MnS  ;  sol- 
uble in  acids,  even  in  acetic  acid. 

115.  NH4OH  precipitates   (incompletely)   whitish 
Mn(OH)2,  which  soon  darkens  in  color.     In  the  pres- 
ence of  salts  of  ammonium  this  precipitate  is  not 
produced  ;  but   the  solution,   on  standing,  soon  be- 
comes cloudy,  and  ultimately  all  the  Mn  is  precipita- 
ted as  brown  Mn202(OH)2. 

116.  NaOH  precipitates  Mn(OH)2. 

117.  Fused  with  Na2C02  and  KN03  on  platinum 
foil,  all  compounds  of  Mn  yield  bright  green  Na2- 
Mn04  ;  soluble  in  cold  H20,  decomposed  by  boiling. 

118.  Compounds  of  Mn  color  the  borax  bead  ame- 
thyst in  the  oxidizing  flame. 

Characteristic  Reactions  ;  114,  117,  118. 

Zinc.     Zn".     Solution,  ZnS04. 

119.  (NH4)2S  precipitates  white  ZuS  ;    soluble  in 
HC1,  but  insoluble  in  acetic  acid. 

1*40.  ^NH4OH  or  NaOH  precipitates  white  gelati- 
nous Zn(OH),  ;  soluble  in  excess  of  either  reagent  ; 
reprecipitated  from  dilute  solution  by  boiling,  but  not 
byNH4Cl.  Of.  312. 

121.  Heated  on  charcoal  with  Na2C03,  compounds 
of  Zn  give  an  incrustation  of  ZnO,  which  is  yellow 
while  hot  and  white  when  cold. 

122.  Moistened  with  Co2N03  and  strongly  heated 


GROUP   IV  ;    REACTIONS.  1& 

before  the  blowpipe,  compounds  of  Zn  yield  an  infus- 
ible green  mass. 

Characteristic  Eeactions  ;   119. 

Cobalt.     Collandiv.     Solution,  Co2N03. 

123.  (NH4)2S  precipitates  black  CoS  ;  insoluble  in 
HC1 ;  soluble  in  HN03  and  in  aqua  regia. 

124.  NH4OH  precipitates  (incompletely)  blue  basic 
salts ;  soluble  in  excess  to  a  brownish  red  solution. 
Salts  of  ammonium  prevent  the  precipitation. 

125.  NaOH  precipitates  the  same  ;  converted  by 
boiling  into  pale  reddish  Co(OH)2.     If  exposed  to 
the  air  without  boiling,  the  precipitate  turns  green. 

126.  KN02  added   to  cobalt  solutions,   which  are 
strongly  acid  with  acetic  acid,   precipitate,  on  stand- 
ing, a  yellow  crystalline  double  salt. 

.  127.  KCN  precipitates  brownish  white  Co(CN)2  ; 
soluble  in  excess  and  reprecipitated  by  HC1  or  H2S04. 
If  to  the  solution  in  excess  of  KCN,  a  few  drops  of 
HC1  be  added  and  the  solution  boiled  for  some  time, 
6KCN,  Co2(CN)fiis  formed,  which  is  not  precipitated 
by  HOI  or  H2S04,  nor  by  NaClO. 

128.  Compounds  of  Co  color  the  borax  bead  deep 
blue. 

Nickel.    Nillandiv.    Solution,  Ni2N03. 

129.  (NH4)2S  precipitates  black   NiS,  slightly  sol- 
uble  in     excess,    forming   a   brown   solution,    from 
which  it  is  reprecipitated  by  boiling  ;  insoluble  in 
HC1 ;  soluble  in  HN03  or  aqua  regia. 

130.  NH4OH    precipitates     (incompletely)     light 
green  Ni(GH)2 ;    soluble   in   excess,  yielding  a  blue 


20  QUALITATIVE    ANALYSIS. 

solution.     Salts  of  ammonium  prevent  the  precipita- 
tion. 

131.  NaOH  precipitates  the  same. 

132.  KN02  in  the  presence  of  acetic  acid  produces 
110  precipitate. 

133.  KON  precipitates  yellowish  green   Ni(CN)2 ; 
soluble  in  excess  and  reprecipitated  by  HC1  or  H2S04, 
even   after   boiling.      If    the   solution  in   excess   of 
KCX  be  boiled  with  NaCIO,  black  Ni2(OH)6  is  pre- 
cipitated.    Cf.  127. 

134.  Compounds  of  Ni  color  the   borax  bead  red- 
dish  brown    in  the   oxidizing   flame  ;    grey   in   the 
reducing  flame. 

Characteristic  Reactions  ;  130,  131. 

ANALYSIS. 

(a)  Add  to  the  solution— or  filtrate  from  Group 
III — (N~H4)2S    till    the    precipitation    is    complete. 
Warm  until  the  precipitate  subsides  ;  filter  and  wash 
with  hot  H20  to  which  a  little   (NH«),S   has   been 
added. 

The  filtrate  may  contain  Groups  V  and  VI.  The 
precipitate  consists  of  one  or  more  of  the  sulphides 
of  Group  IV.  If  light  colored,  Co  and  Ni  must  be 
absent ;  if  dark,  one  or  both  of  these  metals  is  pres- 
ent. 

I.   All  the  group  may  be  present. 

Treat  the  precipitate  with  cold  HOI.  Filter  and 
wash. 

(b)  The  residue  consists  of   CoS,    NiS,    or  both. 
Test  for  Co  with  the  borax  bead  (128).     (1)  If  Co  is 


ANALYSIS.  21 

-absent,  the  bead  shows  the  presence  of  Ni.  Dissolve 
the  residue  in  a  small  amount  of  aqua  regia,  expel 
•excess  of  acid,  dilute  and  confirm  the  presence  of  Ni 
by  special  reactions.  (2)  If  Co  is  present,  dissolve 
the  residue  in  aqua  regia,  expel  excess  of  acid,  add 
.a  cone,  solution  of  KN02  and  acetic  acid.  After 
standing  for  several  hours  in  a  warm  place  the  Co 
is  all  precipitated.  Filter  and  test  the  filtrate  for 
Ni  by  adding  NaOH. 

(c)  The  filtrate  may  contain  ZnCl2,  MnCl2,  or 
both.  Boil  to  expel  H2S,  and  add  excess  of  NaOH. 
Of.  116  and  120.  A  precipitate  is  Mn(OH)2  ;  filter 
.and  confirm  the  presence  of  Mn  by  117.  Test  the 
.filtrate  for  Zn  by  119. 

II.  Co  and  Ni  absent.  Dissolve  in  HC1  and  exam- 
ine the  solution  as  in  I.  c. 

EXERCISES. 

XIX.  Draw   up  a  table   for  the  analysis  of  this 
.group. 

XX.  In  what  other  ways  can  Ni  be  detected  in  the 
presence  of  Co  ? 

XXI.  NH4OH  is  added  to  an  acid  solution  con- 
taining the  members  of  the  first  four  groups  ;  what 
does  the  precipitate  contain  ?     What  change  will  the 
addition  of  an   excess  of   NH4OH  produce  ?     How 
can  the  precipitate  be  examined  ? 

XXII.  To  a  solution  containing  all  of  the  third 
:and  fourth  groups,  (NH4)2S  is  added  ;   of  what  does 
the  precipitate  consist  ?     How  can  it  be  analyzed  ? 

3 


22  QUALITATIVE   ANALYSIS. 

XXIII.  A  solution  is  known  to  contain  Zn  or  Al, 
or  both  ;  how  is  it  to  be  examined  ? 

XXIV.  Describe  the  important  compounds  of  the 
members  of  this  group  and  their  uses. 


Group  Y. 

KEACTIOJSTS. 

Barium.     Ba".     Solution,  BaCl2. 
^  135.   (NH4)2C03    or    Na2C03    precipitates    white 
BaCOg  ;  soluble  in  acids,  even  in  acetic  acid. 

136.  Na2HP04  precipitates  white  Ba2HP04. 
/    137.  H2S04,  or  a  soluble  sulphate,  precipitates,  even 
in  dilute  solutions,  white  BaS04  ;  insoluble  in  acids. 

138.  CaS04    or"1  SrS04    precipitates    immediately 
BaS04. 

139.  K2Cr04  precipitates  yellow  BaCr04 ;  soluble 
in   HC1  ;    reprecipitated   by  NH4OH  ;    insoluble  in 
acetic  acid. 

140.  H2SiF6  precipitates  white  BaSiFfi. 

141.  (NH4)2Ox    precipitates    white    BaC204  from 
moderately  strong  solutions  ;  soluble  in  acetic  acid. 

142.  Barium  compounds  give   a  yellowish   green 
flame  coloration. 

Characteristic  Keactions  ;  137,  142. 

Strontium.     Sr".     Solution,  SrCl2. 

143.  Of.  135  and  136. 

144.  H2S04  precipitates  white  SrS04 ;  slightly  sol- 
uble in  H20,  and  hence  does  not  appear  at  once  in 

less  insoluble  in  acids  than  BaS0, 


GROUP   V  ;    REACTIONS;  23 

145.  CaS04  precipitates  slowly  on  standing  SrS04. 

146.  K2CrO4  precipitates,  only  in  cone,   solutions, 
yellow  SrCr04.     Presence  of  acetic  acid  prevents  the 
precipitation. 

147.  H2SiF6  produces  no  precipitate. 

148.  (NH4)2Ox  precipitates  white  SrC204  ;  soluble 
in  HC1  ;  only  slightly  soluble  in  acetic  acid. 

149.  Strontium    compounds    produce   a   crimson 
flame  coloration. 

Characterictic  Reactions  ;  145,  149. 

Calcium.     Can.     Solution,  CaCl2. 

150.  Of.  135  and  136. 

151.  H2S04   precipitates,    from  strong   solutions, 
CaS04  ;  less  insoluble  in  H20  and  acids  than  SrS04. 

152.  CaS04,  K2Cr04,  and  H2SiF6  give  no  precipi- 
tates. 

153.  (NH4)2Ox  precipitates  white  CaC204  ;  soluble 
in  HOI,  but  insoluble  in  acetic  or  oxalic  acid. 

154.  Calcium  compounds  give  a  dull  red  flame  col- 
oration. 

Characteristic  Reactions  ;  153,  154. 

ANALYSIS. 

The  solution — or  filtrate  from  Group  IV — if  tur- 
bid or  colored,  is  boiled  till  clear  and  filtered  from 
deposited  impurities.  If  acid,  the  solution  must  be 
rendered  alkaline  with  NH4OH.  Add  NH4C1  and 
then  precipitate  by  adding  (NH4)2C03  to  the  warm 
solution.  Filter  and  wash  with  hot  H20. 

The  filtrate  may  contain  Group  VI. 

The  precipitate  consists  of  one  or  more  of.  •the  car- 


24  QUALITATIVE    ANALYSIS. 

bonates  of  Group  V  :    BaC08,  SrCO,,   CuCO,.     Dis- 
solve  in  acetic  acid. 

Preliminary  test.  To  a  small  portion  of  the  solu- 
tion in  HAc,  add  CaS04  solution.  An  immediate- 
precipitate  indicates  that  Ba  is,  and  Sr  and  Ca  may 
be  present  (I).  A  precipitate  after  some  time  shows 
that  Ba  is  absent,  but  Sr  is  and  Ca  may  be  present 
(II).  No  precipitate  indicates  that  Ba  and  Sr  are 
absent  and  that  Ca  alone  is  present  (III). 

I.  All  the  Group  may  be  present.     Add  to  the  HAc 
solution,  K2Cr04  in   slight   excess  and  filter.     The 
precipitate  is  BaCr04 ;   dissolve  in  HC1  and  test  by 
137  and  142. 

The  filtrate  is  made  alkaline  with  NH4OH  and 
(NH4)2C03  added.  A  precipitate  is  SrC08,  CaC03,  or 
both  ;  wash  till  white  and  dissolve  in  HAc.  Test  a 
small  portion  of  this  solution  for  Sr  by  adding 
CaS04  solution,  or  by  the  flame  reaction  (149).  (a). 
If  Sr  is  present,  add  a  dilute  solution  of  (NH4)2S04. 
After  standing  for  some  time,  filter  from  the  precipi- 
tated SrS04  and  test  the  filtrate  for  Ca  by  adding 
NH4OH  and  (NH4)2Ox  (153).  (b)  If  Sr  is  absent,, 
test  at  once  for  Ca  by  153. 

II.  Ba  absent,   Sr  present.     Proceed   as   in  I,  a. 

III.  Ba  and  Sr  absent.     Test  for  Ca  by  153. 


Group  VI. 

REACTIONS. 

Magnesium.      Mg".      Solution,  MgS04. 
155.   NH4OH  and  (NH4)aC08  give  no  precipitates 
in  the  presence  of  salts  of  ammonium. 


GROUP  !VI  ;     REACTIONS.  25 

156.  Na8HP04    produces,     in     the     presence   of 
NH4OH  and  NH4C1,  a  white  crystalline  precipitate  of 
MgNH4P04.     The  precipitation  is  slow  in  dilute  so- 
lutions ;  but  is  hastened  by  warming  and  agitation. 

157.  H2S04,    H2SiF6  and    (NHJ.Ox  produce    no 
precipitates. 

158.  Ignited  on  charcoal,  compounds  of  Mg  yield 
an  infusible  luminous  mass,   which,  on  being  mois- 
tened  with  Co2N03  and  again   ignited,    assumes   a 
pale  rose  color. 

Characteristic  ;  156,  158. 

Potassium.     K1.     Solution  for  reactions,  KC1. 

159.  PtCl4  precipitates,  except  in  very  dilute  solu- 
tions,   yellow  crystalline    PtCl4,2KCl  ;    insoluble  in 
alcohol. 

160.  NaHTr  or  H2Tr  precipitates  white  crystalline 
KHTr  from  concentrated  solutions. 

161.  H2SiFfi  precipitates  white  gelatinous  K2SiF6. 

162.  Potassium  compounds  color  the  flame  violet, 
appearing  reddish-violet  through  blue  glass. 

Characteristic  ;  162. 

Ammonium.       NH4'.       Solution,  NH4C1. 

L63.  PtCl4  precipitates  yellow  crystalline  PtCl4, 
2NH4C1  ;  insoluble  in  alcohol.  On  ignition,  the 
precipitate  leaves  a  residue  of  spongy  platinum. 

164.  NaHTr  or  H2Tr  precipitates  white  crystalline 
NH4HTr  from  concentrated  solutions. 

165.  H2SiF6  gives  no  precipitate. 

166.  Nessler's  solution  produces  a  brown  precipi- 
S* 


26  QUALITATIVE    ANALYSIS. 

tate,  or  in  very  dilute  solutions  a  brownish-yellow 
coloration. 

167.  Heated  with  NaOH,  compounds  of  NH4 
evolve  NH3,  which  is  recognized  by  its  odor,  alkaline 
reaction  and  fuming  with  HC1. 

108.  Heated  on  platinum,  compounds  of  NH4 
volatilize  completely. 

Sodium.     Na1.     Solution  for  reactions,  NaOl. 

169.  Pt014,  NaHTr  and  H2Tr,  give  no  precipitates. 

170.  H2SiF6  precipitates  white  gelatinous  Na2SiFB. 

171.  Sodium  compounds  produce  an   intense  yel- 
low flame  coloration,  which   is   not  visible   through 
blue  glass.     A  crystal  of  K2Cr207  appears  colorless 
when  illuminated  by  the  sodium  flame.    . 

ANALYSIS. 

The  solution — or  filtrate  from  Group  V — is  concen- 
trated by  evaporation  and  a  portion  ignited  on  plati- 
num foil.  If  no  residue  is  lef t,  Mg,  K  and  Na  arc- 
absent.  Test  the  original  solution  or  substance  for 
NH4  by  167. 

If  a  residue  is  left,  Mg,  K,  Na  may  be  present. 
Test  a  small  portion  of  the  concentrated  solution  for 
Mg  by  156,  and  then  proceed  with  the  examination 
for  K  and  Na  by  I  or  by  II  according  to  the  result. 

I.  Mg  is  present.  (a)  Employ  the  flame  tests, 
162  and  171.  A  strong  sodium  flame  masks  a  potas- 
sium flame  ;  but  blue  glass  cuts  off  the  yellow  and  al- 
lows the  detection  of  K  in  the  presence  of  Na. 

Or  (b),  evaporate  the  solution  to  dryness,  ignite 
the  residue  to  expel  salts  of  NH4,  dissolve  it  in  a  lit- 


GROUP   VI  ;     ANALYSIS.  27 

tie  H207  and  add  Ba(OH)2  to  alkaline  reaction  ;  boil, 
filter  ;  The  precipitate  is  Mg(OH)2.  The  filtrate 
contains  Na  and  K,  if  present,  as  hydroxides,  and  the 
excess  of  Ba(OH)8  ;  precipitate  the  Ba  with 
(NH4)2C03,  filter  and  evaporate  the  filtrate  to  dry- 
ness  and  ignite.  The  residue  can  now  contain  only 
Nn.  K.  Test  for  K  by  159,  or  160  ;  for  Na  by  171. 

II.  Mg  is  absent.  Evaporate  the  concentrated  so- 
lution and  ignite  ;  dissolve  the  residue  in  a  little  H20 
and  test  for  K  and  Na  as  in  I.  b. 

A  special  test  for  NH4  is  always  made  by  heating 
a  portion  of  the  original  substance  or  solution  with 
NaOH  (cf.  167). 

EXERCISES. 

XXV.  Draw  up'tables  for  the  analysis  of  Groups 
A"  tind  VI. 

XXVI.  Give  as  many  ways  as  possible  for  detect- 
ing K  in  the  presence  of  Na. 

XXVII.  Devise  other  ways  for  analyzing  this  group. 

XXVIII.  Describe   the   important  compounds  of 
the  members  of  Groups  V  and  VI  and  give  their  uses. 


SECTION   III. 

SYSTEMATIC    ANALYSIS    OF   SOLIDS    AND    LIQUIDS. 


Chapter  I. 

PRELIMINARY     EXAMINATION. 


A.     The    Substance    is    a    Solid. 

I.   A  portion  of  the  powdered  substance  is  heated  in 
a  glass  tube  sealed  at  one  end. 

a.  Water  condenses  on  the  cool  part  of  the  tube. 
This  may  indicate  (1)  adherent  or  enclosed  (decrepita- 
tion) 1I20.     (2)  Salts  containing  H20  of  crystalliza- 
tion (fusion  followed  by  solidification).     (3)  Decom- 
posable hydrates.     The  water  may  be  alkaline  or  acid, 
and  thus  indicate  the  presence  of  NH4  or  a  volatile 
acid. 

b.  Gasex  or  fumes  are  given  off. 

1.  N03  recognized  by  its  color  and  odor,  indicates 
nitrates  or  nitrites. 

2.  Cla,  Bra  or  I2 — color  and  odor  ;  certain  chlorides, 
bromides  or  iodides. 

3.  NH3— odor,  fumes  with  HC1  ;  salts  of  NH4. 

4.  S02 — odor  ;  sulphate  or  sulphite. 

5.  H2S — odor  ;  hydrated  sulphides. 

6.  CN" — odor,  crimson  flame  ;  certain  cyanides. 

7.  C02   extinguishes   a  match,  renders  a  drop  of 
lime  water  turbid  ;  carbonates  and  oxalates. 


PRELIMINARY     EXAMINATION.  291 

8.  CO   burns   with  bine   flame  ;  oxalates. 

9.  02  rekindles  spark  ;    chlorates,  nitrates  or  per- 
oxides. 

10.  N20  rekindles  spark  ;  NH4NOg  or  other  nitrate 
with  a  salt  of  NH4. 

C.   A  sublimate  is  formed.     If  white,  it  may  be  : — 

I.  Salts  of  NH4  ;  heated  with  NaOH  yield*NH3. 
3.   Chlorides   of   Mercury  ;     (a)    Hg0Cl0    sublimes 

without  fusion  ;    is  yellow  while  hot  and  white  when 
cool,     (b)  HgCl2  fuses  before  it  sublimes. 

3.  As203 ;  crystalline,  gives  As  mirror  when  heated 
with  charcoal  in  a  glass  tube. 

4.  Sb203  melts  and  sublimes  in  needles. 
.">.   Certain  organic  acids. 

If  yellow,  it  may  be  :— 

6.  S  ;  sublimes  in  reddish  brown  drops,  which  turn? 
yellow  on  cooling  ;  sulphur  or  certain  sulphides. 

7.  As2S3  ;  reddish  while  hot,  yellow  when  cool. 

8.  HgI2  ;  turns  red  when  rubbed. 

If  dark  or  of  metallic  lustre,  it  may  be  : — 

9.  IQ  ;  feathery  and  black.     Cf.  b.  2. 

10.  HgS  ;  black,  becomes  red  when  rubbed. 

II.  Hg  ;  grey  mirror,  white  globules  when  rubbed. 

d.  The  substance  or  residue  changes  color.  1.  If 
the  substance  blackens  it  may  be  from  the  formation 
of  a  black  oxide,  or  from  the  charring  of  organic 
matter.  In  the  latter  case  smoky  fumes  and  tar  are 
usually  evolved  ;  acetates  give  the  odor  of  acetone  ; 
tartrates  the  odor  of  burnt  sugar  ;  organic  salts  of 
the  alkalies  and  alkaline  earths  yield  carbonates 
which  effervesce  with  acids. 


30  QUALITATIVE    ANALYSIS. 

2.  The  residue  shows  one  of  the  following  changes  : 
Yellow  while  hot,  white  when  cold  ;  ZnO. 
Yellow  brown  "  "  yellow  "  "  SnO... 
Red  brown  "  "  pale  yellow "  "  Bi203. 
Red  brown  "  "  yellow  "  <;  PbO. 
Black  "  "  red  "  "  Fe,03. 

e.   The  substance  fuses   wit '/tout  decomposition  or 

sublimation.     Salts  of  the  alkalies  and  certain  salts 
of  the  alkaline  earths  (nitrates,  chlorides,  etc). 

II.  A  small  portion  is  heated  on  charcoal  before  the 
blowpipe. 

1.  The  substance  deflagrates;  ait  rates  or  chlorates. 

2.  It  melts  and  runs  into   the  charcoal  ;  salts  of 
the  alkalies  and  sonic  salts  of  the  alkaline  earths. 

3.  It  gives  off  S02  ;  sulphur  or  sulphides. 

4.  It  volatilizes  ;  cf.  I.  c. 

5.  It  gives  a  coating  on  the  charcoal  ;  cf.  III.  b. 

6.  An   infusible   white  residue  remains.      Moisten 
with  Co2NOU;nid  ignite  ;  a  blue  color  indicates  Al, 
Si02,  or  })^fs8f8iates  ;  green,  Zn  :  pink  or  rose,  Mg. 

III.  A  small  portion  of  the  finely  jtowdered  sub- 
stance ismfapd  with  NazC03  and  heated  on  charcoal 
in  the  inher^lqwpipe  flame  (reduction). 

a.  Metallic  globules  or  particles  are  obtained  with- 
out a  coating  on   the  charcoal.     Ag,   Cu,   Au  yield 
globules  ;  Pt,  Fe,  Co,  Ni  yield  no  globules,   but  in- 
fusible metallic  particles,  all  of  which  except  Pt  are 
jnagnetic. 

b.  A  coating  on  the  charcoal  is  produced,    with  or 


PRELIMINARY      EXAMINATION.  31 

without   the   formation   of    a   metallic    bead.     The 
coating  is  : — 

1.  White,  very  volatile,  emitting  a  garlic  odor  ;  na 
globule  ;  As. 

2.  White,  less  volatile  than  (1)  ;  globules  usually 
formed,  which  are  brittle  and  hard  ;  Sb. 

3.  Yellow  while  hot,  turns  white  on  cooling,  close 
to  the  substance,  no  globules  ;  Zn. 

4.  Pale  yellow  while  hot,   white  on  cooling,  non- 
volatile ;  globules  formed  with  difficulty,  which  are 
malleable  and  readily  fusible  ;  Sn. 

5.  Lemon  yellow,  volatile;  globules  readily  formed, 
easily  fusible,  soft  and  malleable  ;  Pb. 

6.  Orange  yellow  while  hot,  becomes  lemon  yellow 
on  cooling,  volatile  ;  globules  hard  and  brittle  ;  Bi. 

7.  Reddish-brown  and  volatile  ;  no  globule  ;  Cd. 
C.   The  fused  mass  is  removed  from  the  charcoal  and 

crushed  on  a  silver  coin  with  a  drop  of  water. 

The  silver  is  stained  brown  or  black   (Ag2S)  ;   sul- 
phides or  sulphates  in  the  original  substance. 

IV.  A  small  portion  is  fused  in  a  borax  bead  formed 
in  a  loop  of  platinum  wire. 

BORAX    BEADS. 

Outer  Flame.  Metal.  Inner  Flame. 

HOT.  COLD. 

Green.  Green.  Or.  Green. 

Green.  Blue.  Cu.  Opaque  and  reddish. 

Blue.  Blue.  Co.  Blue. 

Violet.  Brown.  Ni.  Grey  and  cloudy. 

Violet.  Amethyst.  Mn.  Almost  colorless. 

Red.  Yellow.  Fe.  Bottle  green. 


32  QUALITATIVE    ANALYSIS. 

V.  A  clean  platinum  wire  is  moistened  with   HCl, 
dipped  into  the  powdered  substance   and  held  in  the 
-edge  of  the  Bunsen  flame.     The  flame  is  colored 

1.  Yellow,  not  visible  through  blue  glass  ;  Na. 

2.  Violet,  reddish  violet  through  blue  glass  ;  K. 

3.  Crimson,  Sr. 

4.  Orange  red  ;  Ca. 

5.  Green  ;  1I3BOS. 

6.  Yellowish  green  ;   Ha. 

7.  Blue  changing  to  green  ;  Cu. 

VI.  //  the  substance  is  not  a  metal,  a  small  portion 
/x  /nixed  with  cone.  HnSOi  in  a  dry  test  tube  and  the 
mixture  carefully  heated,  if  a  reaction  does  not  take 
place  in  the  rol<(. 

a.  The  following  gases  may  be  evolved  :— 

IIC1,  HBr+Br2,  IQ,  HF,  HCN,  HNO,  HAc,  from 
their  respective  salts  ;  (1IF  is  partially  converted 
into  SiF4,  which  renders  turbid  a  drop  of  I.IaO'Oii 
the  end  of  a  glass  rod)  ;  COQ  from  carbonates  ;  S0g 
from  sulphites  or  thiosulphates  or  by  tartrates  ;  N02 
from  nitrites  ;  II..S  from  sulphides  ;  02  from  perox- 
ides, chromates  (turn  green),  permanganates  (become 
colorless)  ;  CO  from  oxalates  or  ferrocyauides  ;  Cl 
from  hypochlontes  ;  C1204  from  Chlorates. 

b.  Blackening  of    the  mixture   indicates  organic 
matter. 

VII.  After  finishing  the  preliminary  examination, 
treat  the  substance  'with  solvents.    See  chap.  II.  p.  34. 


PRELIMINARY     EXAMINATION.  33 

B.  The  Substance  is  a  Liquid. 

I.  A  few  drops  are  carefully  evaporated  on  platinum 
foil  to  dryness. 

a.  No  residue  remains  ;  H20  and  some  other  vol- 
atile liquids. 

b.  A  residue  remains  ; 

1.  Which  disappears   on   ignition  ;  compounds  of 
NH4,    Hg,    As,    Sb   or   certain   organic   acids.     Cf. 
A.  I.  c. 

2.  Which  changes  color.    Cf.  A.  I.  d. 

3.  Which  fuses  without  volatilizing.     Cf.  A.  I.  e. 

4.  Which  may  be  further  examined  by  A.  II-VI. 

II.  Test  with  Litmus  paper  (blue  and  red). 

a.  The  solution  is  neutral  ;  only  a  few  salts  can  be 
present,  chiefly  chlorides,  nitrates,  and  sulphates  of 
the  alkalies  or  alkaline  earths. 

b.  The  solution  is  acid.     It  may  contain  :  (1)  a 
free  acid  or  acid  salt,  (2)  a  normal  salt  with  acid  re- 
action.    In  the  first  case  a  drop  of  Na2C03  solution 
gives  no  permanent  precipitate  ;  in  the  second,  the 
turbidity  or  precipitate  usually  remains. 

C.  The  solution  is  alkaline.  This  indicates  the 
presence  of  hydroxides,  sulphides,  or  certain  salts  of 
the  alkalies  or  alkaline  earths. 

III.  Proceed  to  the  analysis  by  chap.  III. 


34  QUALITATIVE    ANALYSIS. 

Chapter  II. 

SOLUTION   OF   SOLIDS. 


A.  The  Substance  is  neither  a  Metal  nor 
an  Alloy. 

I.  Add  some  water  to  a  small  quantity  of  the  finely 
powdered  substance  in  a  test  tube  ;  heat,  and  finally 
boil  if  necessary. 

a.  Complete  solution  takes  place.     Dissolve  a  larger 
portion  sufficient  for  analysis,  and  after  examining 
the  solution  with  test-papers  (cf.   chap.   I.   B.   II.), 
proceed  with  the  examination  according  to  chap.  III. 

b.  If  a  considerable  residue  remains  undissolved, 
it  is  usually  best  to  consider  the  substance  insoluble 
in  water,  and  proceed  according  to  II.     Whether  par- 
tial solution  has  taken  place  or  not  can  be  ascertained 
by  filtration  and  evaporation  on  platinum  foil   (cf. 
chap.  II.  B.  I).     If  the  residue  is  quite  small,  it  is 
well  to  filter  and  treat   the   solution   according  to 
chap.  Ill ;  the  residue  according  to  B. 

C.  Soluble  in  water  are  : — All  nitrates,  chlorates 
and  hypochlorites  ;  nitrites  (AgNO^  sparingly)  ; 
acetates  (AgAc  and  Hg^Ac^  sparingly)  ;  sulphates 
except  those  of  Ba,  Sr,  Ca,  Pb  ;  chlorides,  bromides 
and  iodides  except  those  of  Ag,  Hg^  (Pb)  ;  the  bo- 
rates,  carbonates,  oxalates,  phosphates  and  sulphites 
of  the  alkalies  ;  the  oxides,  hydroxides,  sulphides, 
cyanides,  ferrocyanides  and  ferri cyanides  of  the  al- 
kalies and  alkaline  earths  ;  the  fluorides  of  the  alka- 
lies and  of  Ag,  Sn,  Hg,  Bi,  Sb,  Al,  Or  and  Feiv. 


SOLUTION    OF   SOLIDS.  35 

II.  Substances  insoluble  in  water  are  treated  with 
acids  in  the  following   order,    till   they   dissolve   or 
prove   to  be  insoluble   in   all   acids  :     HC1,    HN03, 
aqua  regia.     The  acid  used  is  first  dilute,  then  con- 
centrated ;  and  in  each  case  is  heated  before  passing 
to  the  next.     If  solution  takes  place,  proceed  accord- 
ing to  chap.  Ill,  if  not,  see  III.     It  is  important  to 
avoid  using  an  excess  of  acid,  especially  if  HN03  or 
aqua  regia  is  the  solvent. 

III.  Substances  insoluble  in  wafer  and  acids.     The 
most  common  are  :     sulphates  of  Ba,  Sr,  (Ca),  Pb  ; 
AgCl,    AgBr,    Agl,    AgCN,    CaFa  ;     ignited   Al,03, 
Fe203,  Cr203  ;  Sn02  ;  Si02  and  many  silicates  ;  cer- 
tain ferrocyanides  and  ferricyanides  ;  S  and  C. 

The  preliminary  examination  gives  a  clue  to  the 
composition  of  most  of  these.  C  is  black  and  infus- 
ible, but  disappears  when  ignited  on  platinum  foil 
(graphite  and  gas  carbon  are  scarcely  affected)  ; 
deflagrates  when  heated  with  KN03.  Si02  and  sili- 
cates swim  undissolved  in  a  bead  of  microcosmic  salt. 

(1)  Silicates  are  mixed  with  four  times  the  quan- 
tity  of  K,C03-bNaaC08   and   fused   in   a  platinum 
crucible.     When  cool  add  H20  and  a  little  HC1  and 
evaporate  to  dryness.     On  treating  the  residue  with 
H20,  silica  remains   undissolved,   while   the  metals, 
which  were  originally  present  as  silicates,  go  into  so- 
lution as  chlorides.     If  an  insoluble  silicate  is  to  be 
examined  for  Group  VI,  fuse  with  Ba(OH)2,  or  dis- 
solve in  HF. 

(2)  Sulphates   of  Ba,    Sr,    Ca,   and   A1203,  Fe203 
are  fused  as  in  1  ;    the  fused  mass   is   washed    with 


36  QUALITATIVE    ANALYSIS. 

H20   as  long  as  anything  dissolves  ;    filter  and  dis- 
solve the  residue  in  HC1. 

(3)  PbS04  may  be  dissolved  in  ammonium  tartrate  ; 
AgCl,  AgBr,  Agl  and  AgCN  may  be  dissolved  in 
KCN  or  reduced  by  Zn+H2S04. 

(4)  CaF2  is  decomposed  by  cone.  H2$04  in  a  plati- 
num or  lead  dish. 

(5)  Sn02  is  fused  in  a  porcelain  crucible  with  equal 
parts  of  Na2C03  and  S.     The  fused  mass  is  extracted 
with  H20  and  SnSa  prec.  by  HC1. 

(6)  Insoluble  compounds  of  Cr  are  fused  in  a  plat- 
inum crucible  with  equal  parts  of  Na3C08  and  KN03. 
Boiling  H20  dissolves  from   the   mass   K2(Jr04.     A 
residue  insoluble  in  H20  is  dissolved  in  IIC1. 

(7)  Ferrocyanides  and  ferricyanide*    are   decom- 
posed by  boiling  NaOH  into  ferrocyanides  and  ferri- 
cyanides  of  Na  soluble  in  H20,  and  hydrates  of  the 
metals  soluble  in  acids. 

After  a  solution  is  obtained  it  is  examined  accord- 
ing to  chap.  III. 

B.     The  Substance  is  a  Metal  or  an  Alloy. 
It  is  treated  with  HN03,  and  boiled  if  necessary  : 

a.  Complete  solution  takes  place.     Au,  Pt,  Sb  and 
Sn  are  absent. 

b.  A  residue  is  left  ;  (a)  if  metallic :   Au,  Pt ;  dis- 
solve in  aqua  regia.     (b)  Residue  is  white:  Sb,  Sn, 
or  certain  nitrates  sparingly  soluble  in  HN03.    Treat 
with  H20  ;  the  nitrates  dissolve  ;  to  a  residue,   add 
hot  cone.  H,Tr  ;  Sb  dissolves  and  is  tested  with  H2S  ; 
Sn  remains  undissolved  and  may  be  treated  by  III,  5. 


ANALYSIS    OF     SOLUTIONS.  37 

Chapter  III. 

EXAMINATION   OF   SOLUTIONS    FOR    METALS. 


a.  'Add  to  the  solution  a  few  drops   of    HC1   or 
enough  to  render  it  distinctly  acid,  if  originally  alka- 
line.    A  precipitate  shows  the  presence  of  Group  I 
(cf.  g) ;  see  p.  5,  Analysis. 

b.  To  a  small  test  of  the  solution  in  which  HC1 
has  failed  to  produce  a  precipitate,  or  of  the  filtrate 
from  Group  I,  add  H2S  until  the  odor  is  distinct  af- 
ter shaking  and  warming  gently.     If  no  precipitate 
or  turbidity  is  produced,  pass  to  c.     If  H2S  causes  a 
precipitate  or  turbidity,  add  the  test  to  the  solution 
and  treat  the  whole  with  H2S  (cf.  h)  ;  see  p.  8,  Pre- 
cipitation of  Group  II,  and  pp.  9  and  13,  Analysis. 

c.  To  a  fresh  test  of  the  original  solution,  or  to  a 
test  of  the  filtrate  from  Group  II  from  which  H2S 
has  been  expelled  by  boiling  and  which  contains  no 
ferrous  Fe   (cf.    p.   16,  Analysis),    add   NH4C1   and 
NH4OH.     If  no  precipitate  is  formed,  pass  to  d.     A 
precipitate  shows  the  presence  of   Group  III  (cf.  i) ; 
see  p.  16,  Analysis. 

d.  To  the  test  in  which  NH4OH  procured  no  pre- 
cipitate, or  to  a  test  of  the  filtrate  from  Group  III, 
add  (NH4)2S.     If  no  precipitation  takes  place,  pass 
to  e.     A  precipitate   shows   the   presence   of  Group 
IV ;  see  p.  20,  Analysis. 

e.  To  the  test  which  NH4OH  and  (NH4)2S  failed 
to  precipitate,  or  to  a  test  of  the  filtrate  from  Group 
IV,  add  (NH4)2C03.  *  A  precipitate  shows  the  pres- 


4 


38  QUALITATIVE    ANALYSIS. 

ence  of  Group  V ;  see  p.  23,  Analysis.  If  no  pre- 
cipitate is  formed,  examine  the  solution  or  filtrate 
for  Group  VI according  top.  26,  Analysis. 

Notes  on  the  precipitation  and  separation  of  Groups. 

f.  When  a  group  is  found  to  be  present,  the  group 
reagent  must  be  added  till  it  is  completely  precipita- 
ted.    This  is  the  case,  if,  after  thorough  agitation, 
addition  of  another  drop  of  the  reagent  produces  no 
precipitate,    or  the  solution   smells   of  the   reagent. 
At  the  same  time  a  large  excess  of  the  reagent  is  to 
be  avoided.     The   precipitates   must   be  thoroughly 
washed  to  free  them  from  adhering  solution  which 
may  contain  the  succeeding  groups. 

g.  Group  I.     If  the  solution  is  alkaline,  HC1  may 
precipitate  AsaS3,  SbaS3,  SnS2  (cf.  p.  13,  a)  ;  cyanides 
dissolved  in  KCN  ;    gelatinous  (HO)4Si ;  or  S  from 
alkaline  sulphides.     HC1  may  also  cause  the  evolu- 
tion of  CO,,  H2S,  S02 — sometimes  attended  by  sep- 
aration of  S,  or  HCN(cf.  p.  32,  VI,  a).    SbOCl  and 
BiOCl  are  sometimes  precipitated  at  first  by  dilute 
HC1,  but  dissolve  when  more  acid  is  added. 

h.  Group  II.  The  solution  into  which  H2S  is  led 
must  not  be  strongly  acid  even  with  HC1,  as  in  this 
case  the  sulphides  of  the  group —especially  CdS —  are 
not  readily  precipitated.  The  difficulty  may  be  cor- 
rected by  dilution  or  evaporation.  At  the  same  time 
the  solution  must  be  sufficiently  acid  to  prevent  par- 
tial precipitation  of  ZuS.  Turbidity  on  dilution  in- 
dicates the  presence  of  Bi  or  Sb  (cf.  40  and  70). 

i.  Group  III.  The  precipitate  almost  always  con- 
tains some  Mn  when  this  is  present  in  the  solution 


NOTES   ON    ANALYSIS,  39 

under  examination.  Its  presence  is  shown  by  the 
green  color  of  the  mass  obtained  in  testing  for  Or. 
The  green  manganate  is  decomposed  on  boiling  with 
H20  and  Or  is  detected  in  the  usual  way  in  the  fil- 
trate, cf.  p.  17,  d. 

j.  On  account  of  the  imperfect  separation  of  Groups 
III  and  IV  by  means  of  NH4C1  and  NH4OH,  it  is  in 
some  cases  best  to  precipitate  both  groups  by 
(NH4)2$.  HC1  dissolves  all  but  CoS  and  NiS.  The 
filtrate  is  freed  from  H2S  ;  ferrous  Fe,  if  present,  is 
oxidized  by  HC1  and  KC103,  and  the  solution  when 
cold  is  treated  with  BaC03.  After  shaking  several 
times  during  twenty  minutes,  filter  and  wash.  The 
precipitate  contains  hydroxides  of  Fe,  Or  and  Al, 
and  excess  of  BaC03 ;  the  filtrate  Zn,  Mn  and  Ba013. 

k.  The  precipitate  produced  by  NH4OH  may  con- 
tain or  consist  of  phosphates  or  oxalates  of  the  alka- 
line earths,  as  these  substances  are  only  soluble  in 
acid  solution*.  They  need  not  be  looked  for  if  the 
original  substance  was  soluble  in  H20,  or  if  the  orig- 
inal solution  was  alkaline.  Tests  for  phosphoric  and 
oxalic  acids  should,  however,  be  at  once  made  (a) 
when  a  precipitate  for  Group  III  is  obtained  which 
further  examination  shows  to  contain  none  of  the 
groups ;  (b)  or  when  a  precipitate  is  obtained  for 
Group  III,  and  none  for  Group  V  or  Mg,  although  the 
Preliminary  Examination  has  indicated  the  presence 
of  one  or  more  of  these  metals. 

(1)  If  an  oxalate  is  detected,  a  portion  of  the 
original  substance  is  ignited.  The  oxalate  is  thus 
converted  into  a  carbonate  which  is  dissolved  in  HC1 
and  examined  in  the  usual  way. 


40  QUALITATIVE    ANALYSIS. 

(2)  If  a  phosphate  is  present,  add  to  the  Group 
III  precipitate  a  considerable  quantity  of  metallic 
tin  and  cone.  HN03.  Heat  until  all  the  tin  is  oxi- 
dized. Phosphate  of  tin,  insoluble  in  HN03  is  thus 
formed.  Dilute  with  H20,  filter  and  examine  the 
filtrate,  which  contains  the  nitrates  of  the  metals 
originally  present  as  phosphates,  in  the  usual  way. 


EXERCISES. 

XXIX.  Name    the    most   important   metals  and 
alloys  and  their  uses. 

XXX.  On  adding  the  reagent  for  Group  II  to  a 
solution,   no  precipitate  is  formed,  but  the  solution 
becomes  turbid  ;  to  what  may  this  be  due  ? 

XXXI.  Chromates     give     no     precipitate     with 
NH4OH;  how  then  is  Cr  detected  in  the   ordinary 
course    of    analysis   when  present    in    the   original 
solution  as  chromate  ? 

XXXII.  A  solution   containing  Fe,  Al,   Co,   Cu, 
Zn,    Mn  and  free  acetic  acid  is  treated  with  II88  ; 
what  precipitation,  if  any,  takes  place  ? 

XXXIII.  A  solution  contains  members  of  Groups 
II,  III,  IV  and  V  :     (a)  The  precipitation  by  H2S  is 
incomplete ;  how  may  this  affect  the  examination  of 
the  following  groups  ?     (b)  The  precipitate  formed 
by  H2S   is   complete   but   is   insufficiently    washed; 
what  difficulties  may  arise  in  its  examination  ? 

XXXIV.  Solutions  of  Bi  and  Sb  are  both  precipi- 
tated by  H20  ;  how  can   the   precipitates  be   distin- 
guished ? 


EXERCISES.  41 

XXXV.  Why  must  H2S  be  expelled  from  the  fil- 
trate of  Group  II  before  boiling  with  HN03  ? 

XXXVI.  How  may  the  examination  of  a  solution 
be  simplified  if  it  is  known  that  it  contains  but  one 
metal  ? 

XXXVII.  How   are   the   precipitate   and   filtrate 
obtained  in  the  method  of  separating  Groups  III  and 
IV  by  BaC03  (cf.  p.  39,  j),  to  be  further  examined  ? 

XXXVIII.  A  solution  contains  Al,    Ni,  Mn,   Zn 
and  free  HC1.     After  the  addition  of  a  certain  re- 
agent, H2S  precipitates  ZnS  alone  from  the  solution. 
What  is  the  reagent  employed  ? 

XXXIX.  The   filtrate   from    Group   IV   is   often 
brown.     What  is  the  reason  of  this  ?     How  can  the 
color  be  removed  ? 

XL.  How  can  a  ferrous  salt  be  detected  in  the 
presence  of  a  ferric  compound  ? 

XLI.  How  is  bismuth  chromate  distinguished 
from  lead  chromate  ? 

XLII.  NaOH  is  added  in  excess  to  a  solution  con- 
taining members  of  the  first  four  groups  ;  of  what 
may  the  precipitate  consist  ?  What  change  will  be 
produced  by  boiling  ? 

XLIII.  H2S04  is  added  to  the  filtrate  from  Group 
I  ;  of  what  may  the  precipitate  consist  ? 


FART    II. 


DETECTION    OF    THE    ACIDS. 


SECTION   I. 

REACTIONS   OF    THE    ACIDS. 


Group    I. 

ACIDS    WHICH    ARE    PRECIPITATED    FROM    NEUTRAL 
SOLUTIONS    BY    BaCl2. 

Sub-group  A  :  Acids  whose  Barium  mils  are 
insoluble  in  #6^:— H2S04,  (HJSiF.). 

Sulphuric  Acid  and  Sulphates.  See  Reac- 
tions 137,  16  and  p.  31,  c. 

172.  Free  H2S04  may  be  detected  by  putting  a  few 
drops  of  the  solution  on  writing  paper  and  gently 
warming.  The  acid,  if  present,  will  be  concentra- 
ted and  blacken  the  paper. 

Hydrofluo-silicic  Acid  and  Silico-fluorides.  See  Reactions  140, 
161,  170.  Solid  silico-fluorides  heated  with  cone,  sulphuric  acid 
give  HF,  which  fumes  and  etches  glass,  and  fluoride  of  silicon. 


REACTIONS   OF    ACIDS  ;     GROUP   I,    B.  43 

Sub-group  B:  Acids  wliose  Barium  Salfs  are 
soluble  in  HOI :— H3P04,  H2C03,  HF,  (HO)4Si, 
(HO)8B,  H00x,  H2Tr,  H2Cr04,  H3As04,  H3AsO,, 
<H2S03,  H2S203). 

Phosphoric  Acid  and  Phosphates.  See  Re- 
actions 7,  136,  156. 

173.  If  a  few  drops  of  a  solution  containing  phos- 
phoric acid  or  a  phosphate  be  added  to  a  solution  of 
ammonium  molybdate  in  UNO,,  a  pale  yellow  pre- 
cipitate  of    ammonium   phosphomolybdate    is   pro- 
duced. 

Carbonic  Acid  and  Carbonates.  See  Reac- 
tion 135. 

174.  HC1  and  all  other  free  acids — except  HCN 
and  H2S  —  decompose  carbonates,  usually  with  evo- 
lution  of    C02 — effervescence — which   renders   lime 
water  turbid.     The  effervescence  always  occurs  when 
the  acid  is  in  excess — as  when  the  carbonate  is  added 
to  the  acid. 

Heat  converts  many  carbonates  into  oxides. 

Hydrofluoric  Acid  and    Fluorides.      BaF2  is 

white  and  soluble  in  HC1. 

175.  Heated  with  cone.    H2S04,   all  fluorides  are 
decomposed  with  evolution  of  HF,  which  fumes  and 
etches  glass.     If  the  fluoride  contains  much  Si02,  or 
if  the  decomposition  takes  place  in  a  glass  vessel, 
SiF4  is  formed,  which  is  recognized  by  causing  tur- 
bidity in  a  drop  of  H20. 

176.  Heated  with  KHS04  in  a  borax  bead,  BF3  is 
formed,  which  colors  the  flame  green. 


44  QUALITATIVE    ANALYSIS. 

Silicic  Acid  and  Silicates. 

177.  All  silicates,  except  those  of  the  alkalies  are 
insoluble  in  H20.    HC1  added  drop  by  drop  to  a  strong- 
solution    of  a   silicate,  precipitates  gelatinous  silicic 
acid  ;  but  if  added  to  a  dilute  solution  or  in  large 
excess,  no  precipitate  is  formed.     Some  silicates  are 
decomposed  by  acids— HC1  or  H2S04 — others  must 
be  fused  with  Na2COs  (see  p.  35,  1).     In  either  case, 
evaporation  with  an  acid  to  dryness  must  follow  the 
decomposition,  in  order  to  render  the  silica  insoluble. 

178.  Ba2SiO4  is  decomposed  by  HC1  with  separa- 
tion of  gelatinous  (HO)4Si. 

179.  All  silicates  dissolve  with  effervescence  in  a 
bead  of  NaaC03  ;  but  are  insoluble  in  a  bead  of  mi- 
crocosmic  salt  (NaNH4HP04). 

Boric  Acid  and  Borates.     Ba(B09)a  is  white. 

180  (a)  Alcohol  added  to  boric  acid — or  a  borate 
which  has  been  treated  with  cone.  H2S04 — and 
kindled,  burns  with  a  green  flame,  (b)  This  flame 
coloration  is  also  obtained  by  bringing  a  little  of  the 
powdered  borate,  moistened  with  cone.  H2S04,  into 
the  Bunsen  flame  on  a  platinum  wire  which  has  first 
been  dipped  in  glycerine. 

Oxalic  Acid  and  Oxalates.  See  Reactions 
141,  148,  153. 

181.  (a)  Heated  alone,  oxalic  acid  decomposes 
without  blackening  into  C02,  CO  and  H20  ;  (b)  ox- 
alates  are  converted,  with  evolution  of  CO  and  without 
blackening,  into  carbonates  (cf.  174),  or  with  evo- 
lution of  C02  into  metals,  (c)  Heated  with  cone. 
H2S04,  both  the  acid  and  its  salts  give  off  CO  and 
C02  with  effervescence  and  without  blackening. 


REACTIONS   OF   ACIDS;    GROUP   II.  45 

Tartaric  Acid  and  Tartrates.  See  Reactions 
160,  164. 

182.  BaTr  and   CaTr  are   readily   soluble   in    all 
acids,  even  HAc  (distinction  from  H20x.     cf.  153). 

183.  Solid  tartaric  acid  and  tartrates  blacken  when 
ignited   and  give   the   characteristic  odor  of  burnt 
sugar. 

184.  Heated  with  cone.  H2S04,  both  acid  and  salts 
blacken  and  C02,  CO  and  S0a  are  evolved. 

185.  If    Ag2Tr,    precipitated  from  AgN03   by   a 
neutral    tartrate,    is    nearly    dissolved     by    adding 
NH4OH,   and  the  solution   gently    heated,  the  test 
tube  becomes  coated  with  a  silver  mirror. 

Chromic  Acid,  see  p.  16  ;  Arsenic  and  Arse- 
nious  Acids,  see  p.  12. 

Sulphurous  A  cid  and  Sulphites.  186.  If  to  a  solution  of  ba- 
rium sulphite  in  HC1,  chlorine  water  is  added,  barium  sulphate 
is  precipitated.  Sulphurous  acid  is  a  powerful  reducing  agent 
(cf.  99,  108).  187.  All  sulphites  are  decomposed  by  HC1  with 
evolution  of  sulphur  dioxide,  which  is  recognized  by  its  odor. 

Thiosulphuric  Acid  and  Thiosulphates.  188.  Barium  thiosul- 
phate  dissolves  in  HC1  with  separation  of  S.  189.  HC1  precipi- 
tates from  thiosulphates,  after  a  little,  S  with  simultaneous  evo- 
lution of  sulphur  dioxide. 


Group    II. 

ACIDS    WHICH    ARE    PRECIPITATED    FROM   NEUTRAL 
SOLUTIONS   OF   THEIR   SALTS    BY    AgN03. 

Sub-group  A.     Adds  whose  Silver  Salts  are  in- 
soluble in   HNOt:—H.G\,    HBr,    HI,    HCN,    H2S, 
(H4Fe(CN)6,  H3  Fe(CN)6,  HC10  (precipitates  AgCl)). 
5 


46  QUALITATIVE    ANALYSIS. 

Hydrochloric  Acid  and  Chlorides.    See  Reac- 
tions 1,  10,  19. 

190.  Most  solid  chlorides  yield  HC1  when  heated 
with  cone.   H2S04 ;  or  C12  when  heated  with  HaSO^ 
and  Mn02. 

Hydrobromic  Acid  and   Bromides.     AgBr  is 
pale  yellow  ;  less  soluble  in  NH4OH  than  AgCl. 

191.  PbAc  precipitates  white  PbBr2  ;    less  soluble 
in  H20  than  PbCl2, 

192.  Chlorine  water,  added  to  a  solution  of  a  bro- 
mide, liberates  Br2,  which  colors  the  liquid  yellow  ; 
if  this  solution  be  shaken  with  chloroform,  ether  or 
CS2,  the  Br2  is  dissolved  in  it  with  a  yellow  color, 
which  disappears  on  adding  NaOH,  or  C12  in  excess. 

193.  Heated   with   cone.   H2S04,    bromides    yield 
HBr+Br2  ;  with  Mn02  and  H2S04,  Br2  alone. 

Hydriodic  Acid   and   Iodides.     See   Reactions 
15,  24,  32. 

194.  Agl   is  yellow  ;    very  difficultly   soluble  in 
NH4OH. 

195.  Chlorine  or  bromine  water  sets  I2  free  from 
iodides.     The  liberated  I2  colors  the  liquid  brown, 
and  dissolves  in  chloroform,  ether  or  CS2,  forming  a 
violet  colored   solution.       Excess  of     C12   produces 
colorless  IC13. 

196.  Free  iodine  (cf.  195)  colors  starch  paste  deep 
blue. 

197.  Solid  iodides  yield  violet  vapors  of  I2,  when 
heated  with  cone.  H2S04  or  with  Mn02  and  H2S04. 

Hydrocyanic  Acid  and  Cyanides.     See  Reac- 
tions, 46,  53,  127,  133. 

198.  AgCN  is  white,  insoluble  in  HN03,   soluble 


REACTIONS   OF   ACIDS  ;    GROUP   II.  47 

with  difficulty  in  NH4OH  ;  on  ignition  gives  Ag. 

199.  If   to  a  solution  of  a  cyanide,    NaOH   and 
small   quantities   of   FeS04  and  Fe2016  be  added,  a 
bluish  green  precipitate  is  formed.     On  warming  and 
acidifying  with  HC1,   a  precipitate  of  Prussian  blue 
remains  (cf.  96). 

200.  Most  cyanides  are  decomposed    by   HC1   or 
H2S04  with  evolution  of  HUN,   which  has  the  odor 
of  bitter  almonds. 

Hydrosulphuric  Acid    and   Sulphides.     See 

Reactions  2,  11,  20,  28,  35,  42,  49,  56,  63,  67,  73,  79. 

201.  Most  sulphides,   when  treated  with   HC1  or 
H2S04,  give  H2S,  recognized  by  its  odor  and  by  its 
blackening  paper  moistened  with  PbAc. 

202.  All   compounds  containing  S,    when   heated 
with  Na2C-03   on   charcoal,  yield  Na2S  which,  when 
moistened,  stains  silver  brown  or  black. 

Hydroferrocyanic  and  Hydroferricyanic  Acids  and  their 
Salts.  See  Reactions  91  and  97  ;  90  and  96.  Ferrocyanide  of 
silver  is  white  ;  ferricyanide  of  silver*  orange.  Copper  ferro- 
oyanide  is  brownish  red  ;  ferricyanide,  yellowish  green.  Boil- 
ing NaOH  decomposes  insoluble  ferrocyanides  and  ferricya- 
nides. 

203.  Hypochlorous  Acid  and  Hypochlorites  are  easily  decom- 
posed by  dilute  acids  with  evolution  of  chlorine.  Silver  nitrate 
precipitates  AgCl. 

Sub-group  B.  Acids  whose  Silver  Salts  are  sol- 
uble in  HNOZ  ;— Group  I,  except  H2S04,  HF  and 
H2SiF6;  (HNOf). 

Nitrous  Acid  and  Nitrites.  204.  Silver  nitrate  precipitates 
white  silver  nitrite  ;  soluble  in  |acids  and  in  a  large  excess  of 
water.  205.  Nitrites,  both  solid  and  in  solution,  are  decomposed 
toy  acids  with  evolution  of  red  fumes  ;  the  acid  solution  decol- 
orizes permanganate  of  potassium,  and  colors  starch  paste,  to 
which  KI  has  been  added,  deep  blue. 


48  QUALITATIVE    ANALYSIS. 

Group  III. 

ACIDS   WHICH    ARE    NOT    PRECIPITATED    BY    ANY 

REAGENT:— HN03,HC103,  CH3.CO.OH. 

Nitric  Acid  and  Nitrates. 

205.  Free  HN03  (a)   heated    with    Cu,   gives  red1 
fumes  ;  (b)  boiled  with  fragments  of  quill,   silk  or 
wool,  turns  them  yellow. 

206.  HN03   is   liberated   from    nitrates   by  cone. 
H2S04  and  gives  the  tests  of  205. 

207.  If  to  a  solution  of  a  nitrate,  FeS04  be  added 
and  cone.  H2S04  be  poured  carefully  into  the  test 
tube,  which  is  inclined  so  that  the  acid  runs  down  to- 
the  bottom,    a  dark  ring  will  appear  on  top  of  the 
H2S04,  which  will  be  violet,  red  or  dark  brown,  ac- 
cording to  the  quantity  of  HN03  present.     The  ring 
increases  on  gently  shaking  the  tube,  and  disappears 
on  warming. 

208.  (a)  Solid  nitrates  deflagrate   when   fused  on 
charcoal,     (b)  Heated  in  a  glass  tube,  many  nitrates- 
give  red  fumes. 

Chloric  Acid  and  Chlorates. 

209.  All  chlorates  are  decomposed  by  cone.  H2S04 
with  evolution  of   C1204,  a  greenish  yellow  gas  of 
characteristic  odor.     The  test  must  be  made  with  a 
very  small  quantity  and  no  heat  employed,  otherwise 
the  decomposition  may  take  place  with  explosive  vio- 
lence. 

210.  (a)    Solid   chlorates   deflagrate   on  charcoal, 
(b)  Heated  in  a  glass  tube  or  on  platinum  foil,  02  is 
evolved  and  a  chloride  remains. 


EXAMINATION    FOR    ACIDS.  49 

Acetic  Acid  and  Acetates. 

211.  AgNOg  precipitates  from  not  too  dilute  solu- 
tions white  CH3CO.OAg;  soluble  in  hot  H20  and  in 
NH4OH. 

212.  Heated   (a)  with  cone.   H2S04,   acetates  give 
the  characteristic  odor  of  acetic  acid  ;  (b)  with  cone. 
HQS04    and    alcohol,    the    fragrant    odor    of    acetic 
ether. 


SECTION   II. 

EXAMINATION    FOR   THE    ACIDS. 

A  systematic  course  of  separation  into  groups  and 
individuals,  as  in  the  analysis  for  metals,  cannot  be 
applied  to  the  examination  for  acids.  Their  detec- 
tion must  be  largely  accomplished  by  the  use  of 
special  tests. 

Many  acids  are  detected  or  indicated  in  the  Pre- 
liminary Examination  of  solids  and  treatment  with 
solvents.  If  the  substance  is  in  solution,  addition  of 
HC1  to  precipitate  the  first  group  may  produce  evi- 
dence of  the  presence  of  certain  acids  (cf.  p.  38,  g)  ; 
others  are  reduced  to  bases  by  H2S  in  the  precipita- 
tion of  the  second  group,  and  are  found  as  metals  in 
the  regular  course  of  analysis.  If  the  metals  which 
a  solution  contains  are  known,  the  number  of  acids 
to  be  looked  for  may  be  often  much  reduced  by  con- 
sidering what  acids  may  be  present,  and  what  must 
be  absent  in  solution  with  the  metals  which  have 
been  found.  (Thus,  if  Ba  is  found,  we  need  not 


50  QUALITATIVE    ANALYSIS. 

look  for  H,S04.)  Hence,  as  the  examination  for 
metals  is  likely  to  afford  much  valuable  information 
in  regard  to  the  acids  which  a  substance  contains,  the 
systematic  course  of  analysis  for  metals  always  pre- 
ceeds  the  examination  for  acids. 

As  a  general  rule,  all  the  metals  except  those  of  the 
alkalies,  must  be  removed  from  a  solution  before  ex- 
amining it  for  acids,  as  their  presence  may  interfere 
with  the  detection  of  some  of  the  acids.  If  neither 
As  or  Sb  is  present,  the  other  metals  may  all  be  pre- 
cipitated by  boiling  with  a  slight  excess  of  Na2C03. 
As,  Sb,  as  well  as  the  other  metals  of  Groups  I  and 
II,  may  be  removed  by  leading  H8S  into  the  hot  so- 
lution and  filtering. 

The  solution  from  which  the  precipitated  metals 
have  been  removed  by  filtration  is  boiled  with  addi- 
tion of  HN03  in  very  slight  excess,  until  all  C02  is 
driven  off,  and  then  exactly  neutralized  by  adding  a 
slight  excess  of  NH4OH  and  warming  until  the  solu- 
tion no  longer  smells  of  NH3  and  is  neutral  to  test 
paper. 

The  solution  thus  prepared  cannot  contain 
H9S08,  H3S,03,  H2C03,  HaS,  HC10,  or  HN02. 

If  the  original  solution  contains  no  metals  or  only 
those  of  the  alkalies,  it  is  carefully  neutralized,  if 
necessary,  by  means  of  HN03  and  NH4OH. 

I.  (a)  To  a  portion  of  the  neutral  solution  add 
BaCl2 ;  a  precipitate  shows  the  presence  of  some  one 
or  more  of  the  acids  of  Group  I. 

(b)  To  another  portion  add  HC1  and  BaCl2 ;  a 
precipitate  shows  the  presence  of  Group  I,  Sub- 
group A. 


EXAMINATION    FOR   ACIDS.  51 

If  precipitates  are  obtained  in  both  cases,  any  or 
all  the  members  of  the  group  may  be  present ;  if  only 
in  (a),  Sub-group  B  alone  is  represented. 

(c)  Of  the  acids  of  this  group  the  following  have 
been  found,  if  present,  in  the  preliminary  examina- 
tion and  analysis  for  metals  : — H2Cr04,  H8As04, 
H3As03  as  bases  ;  HSS08,  HaS303,  HaC03,  (HO)4Si, 
HF  and  H2Tr  in  the  preliminary  examination,  treat- 
ment with  solvents  or  on  the  addition  of  HC1  to  pre- 
cipitate Group  I. 

The  presence  of  the  acids  thus  indicated  must  be 
confirmed  by  special  tests. 

II.  (d)  To  a  third  portion  of  the  neutral  solution, 
add  AgN03  ;  a  precipitate  indicates  the  presence  of 
some  one  or  more  of  the  acids  of  Group  II. 

(e)  To  a  fourth  portion  add  HN03  and  AgN03  ; 
a  precipitate  shows  the  presence  of  Group  II,  Sub- 
group A. 

If  precipitates  are  obtained  in  both  cases  any 
or  all  the  members  of  the  group  may  be  present ; 
if  only  in  (d),  Sub-group  A  is  absent.  The  prelimi- 
nary examination  and  analysis  for  metals  have  given 
reactions  for  the  following,  if  present  :  H2S,  HC10, 
HN02,  and  those  common  to  Groups  I  and  II  given 
at  (c).  HC1,  HBr,  HI  and  HCN  are  also  usually  de- 
tected in  the  preliminary  examination.  The  pres- 
ence of  these  acids  is  confirmed  and  that  of  the  others 
of  the  group  detected  by  special  tests. 

HBr  can  be  detected  in  the  presence  of  HI,  by 
adding  chloroform  and  then  chlorine  water  till  the 
violet  color  disappears.  If  the  chloroform  retains  a 
yellow  color,  Br2  is  present. 


•51  QUALITATIVE    ANALYSIS. 

HC1  in  the  presence  of  HBr  and  HI  can  be  de- 
tected as  follows  :  Add  AgN03  in  insufficient  quan- 
tity for  complete  precipitation  and  filter.  Repeat  if 
necessary  until  the  filtrate  is  free  from  Br,  and  IQ  as 
proved  by  the  chloroform  test.  If  the  filtrate  then 
gives  a  precipitate  with  AgN03,  HC1  is  present. 

III.  HN03,  HC10,  and  HAc  have  all  probably 
been  indicated  in  the  preliminary  examination.  Their 
presence  is  confirmed  or  detected  by  special  tests. 

EXERCISES. 

XLIV.  Under  what  condition  can  Ag  and  Cl  be 
present  in  the  same  solution  ? 

XLV.  A  substance  soluble  in  H20  is  found  to 
contain  Pb,  Ca  and  K  ;  what  acids  must  be  absent  ? 

XLVI.  If  Or  is  found  in  the  examination  for  met- 
als, how  can  you  determine  whether  it  was  present  in 
the  original  solution  as  a  chromium  salt  or  as  a  chro- 
mate  ? 

XLVII.  A  solution  contains  Ag  and  free  HNO, ; 
what  acids  must  be  absent  ? 

X  LVIII.  What  will  be  the  result  of  mixing  the  fol- 
lowing solutions  :  (a)  NaCl  and  Pb2N03  ;  (b) 
HgQ2NO,  and  HgCl,  ;  (c)  FeS04  and  BaNO, ;  (d) 
AgS04  and  BaCl,  ? 

XLIX.  An  insoluble  compound  is  found  to  con- 
tain Ag  ;  how  can  the  acid  radicle  be  detected  ? 

L.  How  are  nitrates  and  nitrites  distinguished 
from  each  other  ? 


INDEX. 


ACETIC  Acid,'49. 
Acids.  Examination  for,  49. 
Group  I.  A,  42. 
I.  B,  43. 
II,  A,  45. 

Hydroferrocyanic,  47. 
Hydrofluoric  Acid,  43. 
Hydrofluosilicic  Acid,  42. 
Hydrosulphuric  Acid.  47. 
Hypochlorous  Acid,  47. 

11.  B,  47. 

INSOLUBLE  Substances,  35. 

Ill,  48. 

Iodine,  46. 

Aluminium,  16. 

Iron,  14. 

Ammonium,  25. 

LEAD  4  7. 

Analysis  of  Group  I.  5. 
II   A   9 

MAGNESIUM,  24. 

II    B'  13 

Manganese,  18. 

III,  16. 
IV.  20. 

Mercuric  Salts,  6. 
Mercurous  Salts,  4. 

V,  23. 

Metals,  Examination  for, 

VI,  26. 

Grouping  of,  1. 

Solutions,  37. 

NICKEL,  19. 

Antimony,  11. 

Nitric  Acid.  48. 

Arsenic  Compounds,  12. 

Nitrous  Acid,  47. 

Arsenious  Compounds,  12. 

Notes  on  Analysis,  38. 

BARIUM,  22. 

OXALATES,  39. 

Bismuth,  7. 

Oxalic  Acid,  44. 

Borax  Bead,  Reactions,  31. 
Boric  Acid.  44. 
Bromine,  46. 

PHOSPHATES,  40. 
Phosphoric  Acid,  43. 
Platinum,  14. 

CADMIUM,  8. 

Potassium,  25. 

Calcium,  23.       / 
Carbon,  29,  35.  J 

Preliminary  Examination  of 
Liquids,  33. 

Carbonic  Acid,  43. 

Preliminary  Examination  of 

Chloric  Acid,  48. 

Solids,  28. 

Chlorine,  46. 
Chromic  Acid,  16. 
Chromium,  15. 

REAGENTS,  53. 
SILICIC  Acid,  35,  44. 

Cobalt,  19. 

Silver,  3. 

Copper,  7. 
EXERCISES,  6,  10,  17,  21,  27,  40,  52. 

Sodium,  26. 
Solution  of  Solids,  34. 
Stannic  Salts,  11. 

FERRIC  Salts,  15. 

Stannous  Salts,  10. 

Ferrous  Salts,  14. 

Strontium,  22. 

Flame  Reactions,  32. 

Sulphuric  Acid,  42. 

GOLD,  13. 

Sulphurous  Acid,  45. 

HYDRIODIC  Acid,  46. 
Hydrobromic  Acid,  46. 
Hydrochloric  Acid,  46. 
Hydrocyanic  Acid,  46. 

TABLE  of  Solubilities,  54. 
Thiosulphuric  Acid,  45. 
Tartaric  Acid,  45. 
Tin,  10. 

Hydroferricyanic,  47. 

ZINC,  18. 

14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

LOAN  DEPT. 

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on  the  date  to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


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LD  2li'-50m-8,'61 
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Genera)  Library 

University  of  California 

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